Valley has worst dust pollution in U.S.

by Shaun McKinnon - Apr. 28, 2010 12:00 AMThe Arizona Republic

Day in and day out, residents of Greater Phoenix breathe the dirtiest air in the nation.

Or do they?

In its annual air-quality report card, issued today, the American Lung Association put Phoenix at the top of its list of U.S. cities with the worst year-round dust pollution, as measured by levels of airborne particles that invade the lungs and bloodstream.

But Phoenix can blame its failing grade in part on a lone air-monitoring station in Pinal County, where pollution readings spiked so high, they skewed the average for the entire two-county metropolitan area.

Subtract Pinal County from the equation and Maricopa County earned a passing grade for particulate pollution, a calculation state and county officials quickly noted.

"A single monitor in a distant location shouldn't determine the grade for an entire metropolitan region," said Benjamin Grumbles, director of the Arizona Department of Environmental Quality.

Despite reservations about the report's methodology, he said, the lung association is sincere in its efforts to raise awareness. And, he said, numbers aside, "the serious health risks and poor air quality in some parts of Arizona are real."

Greater Phoenix ranked 11th out of the 25 worst metro areas for ozone pollution, though it was one of 14 metropolitan areas to register fewer days of high ozone levels compared with last year's report.

Ozone is formed when heat and sunshine react with gases emitted from vehicle tailpipes or smokestacks. It reaches its highest levels in the Valley during the spring and summer.

There were bright spots in the report: Metro Phoenix improved its grade for short-term particle pollution, levels measured over 24 hours, from a "D" to a "B." And both Tucson (at No. 6) and Flagstaff (at No. 9) earned spots on the 10 cities with the cleanest air, based on long-term dust pollution.

Across the nation, the lung association said nearly six in 10 Americans breathe unhealthful air, putting them at risk for heart attacks, lung disease and premature death. And the group said new research suggests dust and ozone pose greater dangers than once believed, especially for children, the elderly, the ill and the poor.

"Reducing air pollution can add five months to your life expectancy," said Norman Edelman, the lung association's chief medical officer. "The impact on health is substantial."

To produce its report card, the lung association compiles air-quality data that counties and states send to the U.S. Environmental Protection Agency. For the 2010 survey, the group looked at readings from 2006 to '08, the three most recent years with full data.

The group grades in three categories: ozone, short-term particle pollution and long-term particle pollution. The dust data are based on fine particles, those smaller than 2.5 micrometers in diameter, about one-thirtieth the width of a human hair.

Particles that small can invade the lungs and pass through tissue walls into the bloodstream.

The short-term category measures brief spikes in particle pollution, high levels that last for only part of a day. The long-term category measures levels over a full year. Both pose serious risks.

The group uses the Census Bureau's metropolitan statistical area boundaries to rank air quality by city, which is how Phoenix landed atop the long-term polluters list. The Phoenix-Mesa-Scottsdale statistical area includes Maricopa and Pinal counties.

The troublesome monitoring station sits outside the city of Maricopa, near a string of cattle feedlots, a bulk-grain processor and an ethanol plant. Pinal County installed a fine-dust monitor at the site, known as Cowtown, in 2005 and immediately saw readings off the chart.

Since then, the station has registered some of the highest dust-pollution readings in the nation, said Don Gabrielson, director of the Pinal County Air Quality Control District. The county has worked to control dust and, in recent months, the readings have dropped, but he acknowledged the station still drags the rest of the area down.

"It would be, to my mind, inappropriate or misleading to suggest the data is representative of the entire Phoenix metro area," he said. "It isn't even representative of all of Pinal County."